1. Field of the Invention
The present invention relates to a switching regulator for use in portable devices.
2. Description of the Related Art
In these years, it has been required to save energy also for environmental protection. Devices that use batteries, such as portable devices, are desired to consume less current also in terms of extension of their battery life.
Switching regulators used in such portable devices are known to switch control methods for a light-load time and a heavy-load time. For example, according to one method, reduction in or discontinuity of the inductor current of the inductor of a switching regulator is detected as a light-load time and the control method is switched in response to the detection.
According to this method, a change in the electric potential of, for example, the rectifier diode of the switching regulator is monitored in order to detect a change in the inductor current.
Japanese Laid-Open Patent Application No. 2005-160254 discloses a switching regulator that can extremely reduce loss due to charge and discharge of parasitic capacitors formed between the control electrode and the input and output terminals of a switching device.
According to the conventional switching method, however, there are problems such as increases in the number of circuits and current consumption because analog circuits such as an error amplifier and a comparator are necessary in order to monitor a change in the electric potential.